| Part I Association Studies of Human Adrenomedullin with Type 2 Diabetes Mellitus and Its Renal Complication.Objective To explore the relationship between microsatellite DNA polymorphism of human adrenomedullin gene and type 2 diabetes mellitus within a Chinese population and to evaluate the linkage of AM gene locus to type 2 diabetes mellitus in affected Han Chinese sib pairs, and to investigate the role and mechanism of adrenomedullin in diabetic nephropathy.Methods (1) Among Han Chinese in Jiangsu province ,104 patients with type 2 diabetes mellitus and 77 nondiabetic subjects were collected randomly. 92 type 2 diabetes mellitus sib pairs were enrolled in these serial studies. Polymorphism of microsatellite marker was detected by performing polymerase chain reaction, polyaerylamide gel electrophoresis and silver staining, to investigate the frequency distributions of AM gene microsatellite(CA)n in patients with type 2 diabetes mellitus and nondiabetic subjects and to compare the alleles frequencies and genotype frequencies of AM gene microsatellite(CA)n between diabetic patients with and without nephrophathy; (2) We observed the changes of the expression and secretion of AM, TGF-1 in the cultured human mesangial cells under high glucose condition and the contents of Angll, the laminin and type IV collagen in the supernatants, and the effect of intervention with AM on the changes. Results (1) In Han Chinese, four types of alleles with different CA-repeat numbers: 11,13,14 and 19,appear to exist. The prevalence of AM gene allele frequencies in patients with type 2 diabetes mellitus was significantly different from that in control subjects( x 2 =20.45, P < 0.05). (2) AM gene locus was linked to type 2 diabetes mellitus(t =2.96, P < 0.05). (3) The genotype frequencies andalleles frequencies of AM gene microsatellite(CA)n among the nondiabetic subjects , normal and abnormal albuminuria in diabetic patients were significantly different (x2=61.9, P <0.001; x 2=68.926, P <0.001).The alleles frequencies of AM gene microsatellite(CA)n between normal and abnormal albuminuria in diabetic patients was significantly different ( x 2= 9.276, P= 0.026 ) , whereas no significant difference was found in the genotype frequencies. The allele 4 was more common in diabetic patients with abnormal albuminuria. The reletive risk(RR) was 6.53, P < 0.05. (4) High glucose condition results in increasing the expression and secretion of AM, TGF-1 AngII, laminin and type IV collagen, and AM could reverse the influence of high glucose on the cultured human mesangial cells.Conclusions (1) Polymorphism of microsatellite markers in AM gene is associated with and linked to type 2 diabetes mellitus in Han Chinese. AM gene may be a susceptible gene contributing to the development of type 2 diabetes mellitus and diabetic nephropathy in Han Chinese. (2) The results showed that high glucose condition is one of stimulating factors of AM and the renal protective action of AM may be associated with suppression of AngII, TGF-1 and reducing excessive accumulation of laminin and type IV collagen.Part II Association Studies of vitamin D receptor with Type 2 Diabetes Mellitus and Its Renal Complication.Objective To explore the relationship between DNA polymorphism of human vitamin D receptor (VDR) gene and type 2 diabetes mellitus and diabetic nephropathy within a Chinese population, and to investigate the role and mechanism of vitamin D3 in diabetic nephropathy. Methods (1) By restriction fragment length polymorphism analysis, the allelesfrequencies and genotype frequencies of VDR gene were compared between nondiabetic subjects and type 2 diabetes mellitus with and without nephrophathy; (D Thirty female SD rats were equally divided into three groups at random: normal control rats, streptozotocin-induced diabetic rats, diabetic rats treated with vitamin D3 (25ng.kg-1.d-1). Plasma glucose, HbA|C, serum creatinine, blood uria nitrogen, urinary albumin, serum cholesterol, triglyceride, and serum TGF-1 levels were observed a... |
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